Rare earth doped optical fiber amplifiers (such as, for example, erbium-doped fiber amplifiers) are widely used in a variety of optical communication systems, including wavelength division multiplexed (WDM) networks where different network channels utilize different wavelengths. In a typical communication network, channels may be added or dropped, depending on the volume of traffic passing through the network, outages or the like. When this happens in the optical domain, the cumulative optical power passing through an erbium-doped fiber amplifier changes, which causes a change in the amplification of the signals currently passing through the amplifier.
While there are a variety of schemes well known in the art for addressing some of the power fluctuation problems associated with doped fiber amplifiers, these schemes cannot provide an “instantaneous” smoothing to the amplification of those signals still passing through the fiber amplifier. Thus, some transients in the amplification still occur and degrade the performance of the transmission network.
Thus, it is desired to provide a doped fiber amplifier that is less sensitive to power fluctuations that occur as a transmission network is re-configured (e.g., add/drop of channels).